Doctors Council v. New York City Employees' Retirement System

OPINION OF THE COURT Sullivan, J. Plaintiffs, seven part-time doctors employed by the City of New York or the New York City Health and Hospitals Corporation (HHC), joined by their collective bargaining representative, Doctors Council, have brought this action seeking, inter alia, a declaration that they are entitled to membership in the New York City Employees’ Retirement System (NYCERS). Defendants, NYCERS and the chairman of its board of trustees and its Executive Director seek a declaration also that membership is limited to employees in full-time city service. Both sides moved for summary judgment on the issue. Doctors employed by either the city or HHC fall into two basic categories for payroll purposes — per annum doctors, who are paid according to an annual salary rate; and sessional doctors, paid at an hourly rate. Both are permanent city or HHC employees with regularly scheduled hours of work. Although the common understanding is different, a doctor whose compensation is fixed at a per annum basis is not necessarily a full-time employee, that is, one who, according to NYCERS, works at least 35 hours per week. Both sessional and per annum doctors may be employed either full time or part time. Of the 1,900 doctors employed by the city and HHC and represented by Doctors Council, approximately 1,300 are employed for less than 35 hours per week. All per annum and most sessional doctors have full tenure protection under section 75 of the Civil Service Law or the Doctors Council collective bargaining agreement with the City of New York and HHC. Both part-time per annum and sessional doctors enjoy full collective bargaining rights. They are subject to the same discipline and the same accountability as to hours and performance, including sign-in procedures, as are doctors employed in full-time per annum positions. In January of 1981, the Executive Director of NYCERS, one of the largest retirement systems in the country, with approximately 184,000 active members and 94,000 retirees as of June 30, 1984, and an annual pension payroll of approximately $619,000,000, notified its board of trustees that some part-time employees, primarily doctors and dentists, had been accepted as members. After reviewing the recommendations of a sub — 383 — committee which had been established to study the issue, the board subsequently passed a resolution, dated November 6, 1981, stating that it "does not have the power * * * to direct that part-time employees shall be eligible for NYCERS membership.” The board resolved, however, that, since some part-time employees had erroneously been accepted into membership, all those who had been accepted prior to November 6, 1981, the date of the resolution, would be continued as members. The November 6, 1981 resolution also instructed the Executive Director to implement administrative procedures to prevent any such recurrence. As of November 8, 1981, all of the plaintiff physicians held positions requiring less than 35 hours of work per week. Three of them, Bhuvaneswar, Vennema and Tannenbaum, although employed in various positions before that date, had not filed applications for membership. In December 1981, these three plaintiffs filed requests under Laws of 1981 (ch 1044) for retroactive membership. Similarly, in December of 1981, the other four plaintiff physicians, Kligman, Prensky, Seligman and Wiederlight, although members of NYCERS prior to November 6, 1981, requested a transfer of benefits status to Tier I from Tier II or Tier III. NYCERS refused to process these applications on the ground that part-time employees are not eligible for membership. Plaintiffs thereafter commenced this action, seeking declaratory and injunctive relief and asserting four causes of action: that the plaintiff physicians are entitled to NYCERS membership under the relevant statutory provisions; that defendants are estopped from denying the right of the four plaintiffs who are currently NYCERS members to transfer to Tier I retirement status; that they are also estopped from denying the applications for retroactive membership of the three plaintiffs who were not members before November 6, 1981; and that the denial of the plaintiff physicians’ applications is prohibited by the Equal Protection and Due Process Clauses of the New York and the United States Constitutions. The parties have stipulated that any final judgment in this action will apply to all other doctors and dentists represented by Doctors Council who have been refused membership or transfers of status because of their part-time employment. According to its present Executive Director, who has been with the retirement system in various capacities since 1958, NYCERS has had a "continuing” and "longstanding” policy of excluding part-time employees from membership. NYCERS — 384 — acknowledged that some part-time employees had. been accepted as members, but insisted that such instances were the result of error, usually caused by the absence of complete and accurate information as to the nature of the applicant’s job or a lack of awareness by staff members that the applicant’s job title represented a part-time position. According to NYCERS, its policy, upon discovery of such mistakes, has been to terminate the part-time employee’s membership and refund all of his or her contributions. To support their position, defendants submitted two internal memoranda, one dated November 26, 1970 and the other, October 12, 1971, from Arthur Van Houten, the then secretary of NYCERS, in which he informed the staff that, under NYCERS’ rules and regulations, part-time employees were excluded from membership. Defendants submitted a third memorandum, also signed by Van Houten and dated August 16, 1971, denying NYCERS membership to a transcribing typist in the Department of Social Services because she was a part-time employee. According to Van Houten, these 1970-1971 memoranda “reflect the legal advice which I received at that time from the Corporation Counsel to the effect that, pursuant to the applicable law and regulations governing the operations of NYCERS, part-time employees were not eligible for membership.” That advice, based on a review of the pertinent statute, NYCERS’ rules and an earlier 1936 opinion of the Corporation Counsel was ultimately set forth in a letter from the Corporation Counsel to Van Houten, dated November 24, 1974, stating, ”[I]t has been the consistent practice of the Retirement System for at least 36 years, and apparently from the inception of the System, to follow the foregoing interpretation, as set forth in the [1936] opinion of the Corporation Counsel, that part-time employees are ineligible for membership.” In an affidavit in support of plaintiffs, however, Van Houten maintained that the Corporation Counsel’s 1974 opinion was a “new position”, and that NYCERS’ policy, to the contrary, had been to accept part-time employees as members. Van Houten cited the minutes of meetings of the Board of Estimate, which, until 1969, had acted as NYCERS’ board of trustees, claiming that “a review of the first volume of those minutes for the years 1930, 1940, 1950, 1960, and 1965 indicates that per diem, per session, hourly and part-time employees were both members of NYCERS and received retirement benefits from the system in significant numbers in each of those years.” Van — 385 — Houten further pointed out that "NYCERS members in those payroll categories included not only doctors, but also non-per annum employees in [a variety of titles, including laborer, cleaner, dock-builder, senior stationary engineer].” In reply, defendants presented an analysis of the Board of Estimate minutes upon which Van Houten relied to demonstrate that of the approximately 131 employees mentioned in the Board minutes only two ever sought retirement credit on the basis of less than full-time employment. One of these part-time employees was apparently a doctor, paid on a per session basis. Most of the employees mentioned in the Board minutes were classified as "per diem” or "hourly”, terms which, according to defendants, only describe the method by which an employee’s pay is computed and do not, contrary to Van Houten’s conclusion, indicate part-time employment status. In fact, a review of the still-existing NYCERS files of the per diem and hourly employees mentioned in the Board minutes disclosed that they all had been full-time employees.1 Plaintiffs also submitted the affidavits of Donald C. Meyer, the Executive Director of Doctors Council, and Robert Pick, a former city negotiator. Dr. Meyer stated that he had been employed by the city as a sessional dentist since 1957 and had been a NYCERS member since 1958, and that such membership was required as a condition of his employment. Pick, as Assistant Director of Labor Relations for the city between 1966 and 1979, was charged with the responsibility of negotiating contracts covering professional medical personnel employed by the city and HHC. During the 1960’s the city employed approximately 1,000 physicians represented by Doctors Council, most of whom worked on a part-time, per session and hourly rated basis. According to Pick, these doctors were entitled to membership in NYCERS as "part of the terms and conditions of [their] employment”. When Pick negotiated the first contract with the newly established Doctors Council for the city in 1972, "there was no issue raised or made over the continued entitlement of doctors, whether full-time, part-time or per session to membership in NYCERS.” Pick further stated that, as HHC’s Director of Labor Relations from 1980 to 1982, he was aware that doctors were afforded membership in NYCERS, "irrespective of their per annum, per session or — 386 — full-time/part-time status.” Plaintiffs allege that of the 1,300 part-time doctors currently in the employ of the city or HHC, approximately 500 are NYCERS members. Finally, NYCERS demonstrated that, as of December 31, 1983, the city engaged 45,504 part-time employees, exclusive of HHC’s part-time employees, whose numbers could not be determined since HHC’s statistical data was not available. Only 286 of these part-time employees were NYCERS members. The aggregate annual earnings of the 45,218 part-time employees who were not NYCERS members were $254,027,502. On average, the city funds more than 80% of a member’s retirement benefits. The Chief Actuary of the five New York City actuarially funded retirement systems estimated that, if all part-time city employees were permitted to become members of NYCERS, the increased annual cost to the city would be in excess of $27,500,000, a figure exclusive of the additional costs which would be incurred were HHC’s part-time employees included. Moreover, according to the Chief Actuary, if the city’s part-time employees chose to purchase premembership service credit, assuming five years to be the norm, the city and related agencies would be required, by "conservative estimate”, to increase their annual pension contributions by $34,000,000. Special Term denied plaintiffs’ motion for summary judgment and, on their cross motion, granted summary judgment to defendants dismissing the first (statutory) and fourth (equal protection) causes of action, and declaring accordingly. It denied the cross motion with respect to the second and third (estoppel) causes of action. The parties have cross-appealed, each from the adverse aspects of the determination. We modify only because Special Term should not have dismissed the first and fourth causes of action when it declared in defendants’ favor on these causes. (Lanza v Wagner, 11 NY2d 317, 334; New York Mobile Homes Assn. v Steckel, 11 AD2d 751, affd 9 NY2d 533.) Membership in NYCERS is limited to persons in "city-service” (Administrative Code of City of New York § B3-3.0, recodified as § 13-104), which is defined, in relevant part, as "service, whether appointive or elective, as an officer or employee of the city or state of New York, of any agency thereof and of any court, so far as such service is paid for by the city”. (Administrative Code § B3-1.0 [3] [a], recodified as § 13-101 [3] — 387 — [a].) Admittedly, the statute nowhere specifically defines the term "service” as either full time or part time. While arguably encompassing persons performing part-time service, the general definition of "city-service”, when considered in the context of the myriad job classifications within the sprawling city work force, cannot be construed to include part-time employment. The city’s employment structure contains literally thousands of job classifications and numerous compensation variables. It hires employees who work a regular 35-hour week as well as those special or temporary employees who work a few days or weeks a year, or on a seasonal basis. Moreover, some city employees are paid from city treasury funds while others are paid from Federal funds; still others are compensated from the fees generated by the particular city agency for which they work, rather than the city treasury, while the employees of quasi-public institutions such as the Metropolitan Museum of Art and the New York Zoological Society are paid from city funds. (See, Rules and Regulations of Board of Estimate, NYCERS § 11 [a] [c] [1947].) Indeed, the Legislature recognized the need for flexibility in applying NYCERS’ general terms, including "city-service” (Administrative Code § B3-1.0 [3] [a], recodified as § 13-101 [3] [a]), to the city’s complex employment structure. Administrative Code § B3-1.0 (recodified as § 13-101), the definitional section of the NYCERS act, contains a caveat: "The following words and phrases as used in this title, unless a different meaning is plainly required by the context, shall have the following meanings”. Thus, by the use of the phrase "unless a different meaning is plainly required by the context”, the Legislature not only foresaw the need for, but explicitly sanctioned, administrative interpretation of NYCERS’ general terms, including "city-service”. Nor, in determining the scope and meaning of the term "city-service”, are we foreclosed from inquiry into the statute’s legislative history or consideration of its administrative interpretation merely because the Administrative Code’s general language may arguably be broad enough to encompass part-time employees. (See, New York State Bankers Assn. v Albright, 38 NY2d 430; see also, Uniformed Firefighters Assn. v Beekman, 52 NY2d 463, 471.) In construing a statute the "[a]bsence of facial ambiguity is * * * rarely, if ever, conclusive.” (New York State Bankers Assn. v Albright, supra, at 436.) The "plain meaning rule”, upon which plaintiffs rely, has been resoundingly rejected by the Court of Appeals. — 388 — "When aid to construction of the meaning of words, as used in the statute, is available, there certainly can be no 'rule of law’ which forbids its use, however clear the words may appear on 'superficial examination’ ” (supra, at 437). "Inquiry into the meaning of statutes is never foreclosed at the threshold” (supra, at 436). Thus, an agency charged with the implementation of a statute is not bound by a plain meaning statutory interpretation which was never intended nor mandated by its terms. In any event, section B3-1.0 (3) (a) (recodified as § 13-101 [3] [a]) of the Administrative Code does not specifically include part-time city employees within its definition of "service”. As already noted, it fails to define "service” in terms which either include or exclude part-time service. It is well settled that the construction given a statute by the agency responsible for its administration, if not irrational or unreasonable, will be upheld (Matter of Howard v Wyman, 28 NY2d 434, 438; Matter of Meko Holding v Joy, 107 AD2d 278, 283; Matter of Transamerica Ins. Group [Markland], 107 AD2d 591, 593), particularly where, as here, "the interpretation of a statute or its application involves knowledge and understanding of underlying operational practices”. (Kurcsics v Merchants Mut. Ins. Co., 49 NY2d 451, 459.) Moreover, when, as here, the common experience has been to acquiesce in the "practical construction” of the administering agency for a long period of time, the administrative interpretation " 'is entitled to great, if not controlling, influence.’ ” (Kranker v Levitt, 68 Misc 2d 224, 227 [quoting Chicago v Sheldon, 9 Wall (76 US) 50, 54], affd 30 NY2d 574; accord, Uniformed Firefighters Assn. v Beekman, supra, 52 NY2d, at 472.) Although a legislative history is not available, NYCERS has maintained a policy of excluding part-time employees from membership since its creation in 1920 (L 1920, ch 427). The earliest available evidence of its interpretation of section B31.0 (3) (a) (recodified as § 13-101 [3] [a]) is found in two opinions of the Corporation Counsel issued in 1936 and 1937. In the 1936 opinion, which dealt with a NYCERS member’s claim for premembership credit for service as counsel to four different city-wide investigative committees, the Corporation Counsel laid down general guidelines for determining whether an employee is engaged in "city-service” within the meaning of section B3-1.0 (3) (a) (recodified as § 13-101 [3] [a]). These guidelines were subsequently incorporated into rule 11 (f) of — 389 — NYCERS Rules and Regulations, adopted in 1947.2 As even plaintiffs acknowledge, NYCERS Rules and Regulations, including rule 11 (f), were not intended to change the practices of the retirement system, but were to serve as a codification of these practices. Both the general guidelines and rule 11 (f) require full-time service as a condition of eligibility for NYCERS membership. In his 1937 opinion, the Corporation Counsel referred to the "general standards” in the 1936 opinion and reaffirmed his view that full-time service was a prerequisite to NYCERS membership. Furthermore, it is significant that the Legislature has never seen fit to amend the Administrative Code to bar the exclusion of part-time employees from NYCERS membership, particularly in view of the 1977 adoption by the Legislature of a new State pension plan which, for the first time, permitted part-time employees to become members of the State pension system. (Retirement and Social Security Law § 500 [b] [4] [a].) In enacting this legislation, the Legislature provided that New York City employees would "be eligible or ineligible for membership in [NYCERS] in the manner provided for by the relevant provisions of the New York city administrative code and other relevant laws and rules and regulations.” (Retirement and Social Security Law § 500 [b] [1].) The Legislature’s failure to extend NYCERS membership eligibility to part-time city employees must be viewed as an acceptance of NYCERS’ practice of excluding part-time employees from membership. (See, Uniformed Firefighters Assn. v Beekman, supra, 52 NY2d, at 472.) The record contains other evidence pointing to NYCERS’ long-standing policy of limiting membership to full-time employees. Its annual reports for the years 1969-1979 state that membership is available to "City employees, in full-time positions.” The already noted 1974 opinion of the Corporation Counsel reaffirmed that part-time employees were not eligible for NYCERS membership. The present Executive Director and the Chief of NYCERS Member Services Division both state that the administrative practice has been to exclude part-time employees from membership. This position is further but — 390 — tressed by numerous letters from the Chief of the Membership Division, dated between 1971 and 1981, rejecting membership applications on the basis of part-time employment. Thus, on the basis of its interpretation of "service” (Administrative Code § B3-1.0 [3] [a], recodified as § 13-101 [3] [a]) as being synonymous with full-time service, NYCERS has clearly demonstrated a policy and practice of excluding part-time employees. Although Van Houten, the then NYCERS Executive Director, wrote two staff memoranda in 1970 and 1971 stating that part-time doctors and dentists were exempt from the general rule excluding part-time employees from membership, a search of NYCERS’ records fails to reveal any justification for the exception, the origin of which is attributed to administrative mistake. It is clear that the board of trustees never approved any such exception. Plaintiffs argue that provisions of the Administrative Code other than section B3-1.0 (3) (a) (recodified as § 13-101 [3] [a]) compel the conclusion that part-time employees are entitled to NYCERS membership. For example, they cite section B3-3.0 [1] (recodified as § 13-104 [1]) which defines those who may become NYCERS members as "[a]ll persons in city-service, as defined in this title”. That provision, however, does not require the extension of NYCERS membership eligibility to those employed on a part-time basis,3 since it extends membership only to those in "city-service” as that term is defined in section B3-1.0 (3) (a) (recodified as § 13-101 [3] [a]). Plaintiffs also argue that section B3-5.0 (b) (recodified as § 13-107 [b]), which requires NYCERS’ board of trustees to "fix and determine how much service rendered in any year shall be the equivalent of a year of service and of parts thereof’, mandates the board to permit part-time employees to become members. They also cite rule 24 of NYCERS Rules and Regulations, which provides for the conversion of part-time and sessional service to full-time equivalent service.4 Neither sec — 391 — tion B3-5.0 (recodified as § 13-107), nor rule 24, however, pertains to NYCERS membership eligibility. Section B3-5.0 (a) (recodified as § 13-107 [a]) expressly states that it is "[s]ubject to the following and to all other provisions of [this act]”. The application of section B3-5.0 (recodified as § 13-107) and rule 24 is accordingly limited to those engaged in "city-service” as defined in section B3-1.0 (3) (a) (recodified as § 13-101 [3] [a]). (See, e.g., Matter of Keane v Leary, 34 AD2d 771, affd 29 NY2d 713.) Finally, plaintiffs cite section B49-9.3 (a) (ii) (recodified as § 12-126 [a] [ii]), which, insofar as is relevant, defines a "city retiree” for purposes of determining eligibility for receipt of retiree health benefits as: "[a] person who: (1) is receiving a retirement allowance, pension or other retirement benefit from a retirement or pension system maintained by the city; and (2) immediately prior to such person’s retirement as a member of such system, was a city employee, or was an employee of the board of education employed under terms prescribing a work week regularly consisting of twenty or more hours during the fiscal year”. Plaintiffs argue that this section clearly contemplates retirees who were part-time employees; otherwise, the minimum requirement of a 20-hour work week for retirement health benefits would be unnecessary. This claim is unavailing since the only portion of the section relating to part-time employment, i.e., a work week of less than 35 hours, is limited to Board of Education employees. Whether full time or part time, employees of the Board of Education, which has its own separate retirement system, are not eligible for NYCERS membership. (Administrative Code § B3-1.0 [3] [a], recodified as § 13-101 [3] [a].) Furthermore, to the extent that section B49-9.3 (a) (ii) (recodified as § 12-126 [a] [ii]) specifically provides that the term "employee”, as used in that section, includes part-time employees, it militates against plaintiffs’ argument that part-time employees are generally included within the meaning of that term. We thus agree with Special Term that the Administrative Code does not mandate NYCERS to extend membership to part-time employees. In the absence of a genuine issue of fact, summary judgment was properly granted (Barr v County of Albany, 50 NY2d 247, 254) on the first cause of action alleging that the plaintiff doctors are entitled to NYCERS membership under the relevant statutes. In asserting a denial of equal protection, plaintiffs argue that there is no "rational basis to distinguish between part392 time and full-time doctors with respect to pension entitlement.” The Supreme Court has consistently recognized that "the Fourteenth Amendment does not deny to [the] States the power to treat different classes of persons in different ways.” (Reed v Reed, 404 US 71, 75; see, Matter of Tolub v Evans, 58 NY2d 1, 8; Montgomery v Daniels, 38 NY2d 41, 61.) To withstand equal protection analysis, a classification which, inter alia, provides disparate compensation or benefits to public employees must be "reasonable, not arbitrary, and must rest upon some ground of difference having a fair and substantial relation to the object of the legislation, so that all persons similarly circumstanced shall be treated alike.” (Royster Guano Co. v Virginia, 253 US 412, 415; cf., Weissman v Evans, 56 NY2d 458, 466.) We find that a classification which distinguishes between full-time and part-time employees is rationally based and substantially related to the allocation of city resources. To provide NYCERS membership solely to full-time employees is to recognize that only employees who devote their careers in full service to the city should be entitled to the substantial benefits of the retirement system. As already noted, NYCERS had approximately 184,000 active members and 94,000 retirees as of June 30, 1984. Its annual pension payroll was approximately $619,000,000. If the 45,504 part-time employees working for the city and various related independent agencies as of December 31, 1983, excluding HHC’s, were to become NYCERS members, the increased annual cost to the city and its related agencies would be in excess of $27,500,000. In addition, the "conservative estimate” of the cost of purchasing premembership service credit for these part-time employees would be $34,000,000. The expenditure of such a considerable sum as against the saving to the public fisc provides the rational basis for excluding part-time employees from NYCERS membership. That the difference in treatment works to the disadvantage of the part-time employee is, from a constitutional standpoint, of no moment. "[E]very line drawn by a legislature leaves some out that might well have been included.” (Village of Belle Terre v Boraas, 416 US 1, 8.) Plaintiffs’ argument that the distinction is arbitrary because Congress and the State Legislature have included part-time employees in the Social Security and the State pension systems, respectively, is unpersuasive. The Federal, State and city governments, understandably, all have different fiscal — 393 — resources and policies, and may choose to include or exclude part-time employees without regard for what another level of government has done. In any event, a fiscal decision which concerns an estimated expenditure of $34,000,000 is hardly an inconsequential matter, as plaintiffs argue. The distinction between employees is clear and well recognized and does not violate the Equal Protection Clause. Special Term also held that issues of fact barred dismissal of plaintiffs’ estoppel claims, which apply to all seven of the plaintiff doctors. We agree. Plaintiffs allege, and defendants deny, that part-time doctors were admitted to NYCERS regularly, rather than as a result of a "mistake” by NYCERS administrators, and that the plaintiff doctors relied on NYCERS’ past practice concerning membership in determining to accept part-time employment with the city or HHC. Estoppel is not available against a governmental entity to create a right where none exists. (Matter of McLaughlin v Berle, 71 AD2d 707, 708, affd 51 NY2d 917.) Thus, a party cannot avoid the effect of a clear statutory provision through the failure of a governmental agency to enforce the law. (Matter of Galanthay v New York State Teachers’ Retirement Sys., 50 NY2d 984; Matter of Owens v McGuire, 121 AD2d 292, 295; Matter of Syrewicz v New York State Teachers’ Retirement Sys., 79 AD2d 1072; Matter of Hauben v Goldin, 74 AD2d 804, 805; Matter of McLaughlin v Berle, supra, 71 AD2d, at 708.) In certain circumstances, however, estoppel is available against a governmental entity. "[WJhere a governmental subdivision acts or comports itself wrongfully or negligently, inducing reliance by a party who is entitled to rely and who changes his position to his detriment or prejudice, that subdivision should be estopped from asserting a right or defense which it otherwise could have raised.” (Bender v New York City Health & Hosps. Corp., 38 NY2d 662, 668; see also, La Porto v Village of Philmont, 39 NY2d 7.) As both Bender and La Porto (supra) make clear, a governmental entity may be estopped from taking action where it is acting within the realm of discretion rather than in accordance with a statutorily imposed mandatory duty. In Bender, the plaintiffs had failed to file a timely notice of claim against the Health and Hospitals Corporation, as required by General Municipal Law § 50-e, but instead had filed one with the city. Although finding that the failure to serve the proper party did not fall within the class of "nonprejudicial mistakes or irregularities” which, by express statutory authority, were judicially — 394 — correctable (supra, 38 NY2d, at 667) the court, nonetheless, held that the defendant could be estopped from asserting the defense of failure to file a timely notice of claim, since the notice of claim requirement is not jurisdictional and may be waived in appropriate circumstances. Although the court spoke in terms of acquiescence, rather than estoppel, to which it "bears a close resemblance” (supra, 39 NY2d, at 12) estoppel was similarly available in La Porto. There, a village had failed, for a period of more than 80 years, to assert its authority for taxation and other purposes over certain lands officially within its territorial limits but outside its boundaries as delineated by the map and description which it filed with the Secretary of State. While emphasizing that "where the State Legislature has acted to establish or alter municipal boundaries, the doctrine of acquiescence has no application” (supra, at 13), and, in effect, reaffirming the principle that estoppel cannot operate to defeat an express statutory mandate, the court held, nonetheless, that estoppel was available to support the conclusion that the assumed boundaries are the true boundaries where the property owners and other local governments relied to their detriment upon the village’s inaction. The courts have applied the doctrine of estoppel against a governmental entity under similar circumstances so long as the agency is not estopped from enforcing an affirmative statutory mandate. (See, e.g., Landmark Colony v Board of Supervisors, 113 AD2d 741; Matter of 1555 Boston Rd. Corp. v Finance Adm’r of City of N. Y., 61 AD2d 187.) Here, the statute does not require defendants to deny NYCERS membership eligibility to part-time employees. Indeed, defendants permitted 4 of the 7 plaintiff doctors who were admitted to membership prior to 1981 to retain that membership, and "grandfathered” other employees in the same situation into the retirement system. As in Bender and La Porto (supra), defendants may be estopped from exercising their discretion to exclude part-time employees from NYCERS membership if the plaintiff doctors relied, as alleged, upon express assurances or a practice, even if unauthorized, of extending NYCERS membership eligibility to part-time and sessional doctors. The plaintiff doctors claim that they entered city or HHC employment and based their career, savings, insurance and retirement plans upon expectations of receiving full NYCERS — 395 — benefits.5 In many cases, they claim, doctors entered city service primarily to be eligible for retirement benefits, and did so on the basis of representations by city or HHC administrators at the time of their hiring that they would be so eligible. Indeed, 4 of the 7 individual plaintiffs are NYCERS members who have had pension contributions deducted from their paychecks for many years. The doctrine of equitable estoppel should be available in just such circumstances. It would preclude a party from exercising a power he might otherwise legally exercise, when to do so would result in severe prejudice or injury to another party who has placed himself in a position of risk in reliance upon the express or implied representations of the first party. Accordingly, the order and judgment (one paper) of the Supreme Court, New York County (Arthur E. Blyn, J.), entered October 3, 1985, should be modified to strike therefrom the provisions dismissing the first and fourth causes of action and, as so modified, affirmed, without costs or disbursements. Footnotes [1] One NYCERS member who had worked full time for approximately 21 years of his 23-year career had a short period of part-time service in the middle of his career. This employee had joined NYCERS as a full-time employee and retired as a full-time employee. [2] Rule 11 (f) provides: "No person who is paid other than a regular per annum salary, who renders less than full-time service [sic] not required to keep the regular office hours of the agency in which he renders service, is not required to report at a given time or place and is not subject to the discipline of the agency shall, by such service, acquire any right or benefit in the retirement system.” [3] Plaintiffs presumably cite section B3-3.0 (1) (recodified as § 13-104 [1]) because it mandates membership for "city-service” workers in the competitive class. Although plaintiffs contend that "[m]any part-time and sessional doctors hold civil service positions in the competitive class”, it should be noted that all of the plaintiff doctors stated that they served in noncompetitive job classifications. [4] That rule 24 refers to "service paid for by the hour, session, night, etc.” does not mandate eligibility for part-time employees. A full-time employee can be compensated on a per diem or hourly basis. Employees of the Rapid Transit Railroad System, for example, are generally full-time employees compensated on an hourly basis. [5] This claim may be difficult to sustain in the case of the three plaintiff doctors who, although employed before that date in various positions, did not apply for membership until after November 6,1981.